This proposal is designed to determine the usefulness of a protective environment in the management of patients at great risk of infection. The protective environment consists of sterile laminar air flow (LAF) rooms, sterile diet and topical antibiotics. After informed consent, patients will be randomized into LAF isolation or conventional mask isolation. Patients with metastatic carcinoma of ovary, testicle or breast will receive high doses of cyclophosphamide. Patients with acute leukemia or aplastic anemia will receive cyclophosphamide and/or whole body irradiation followed by an allogeneic marrow transplant. Objectives of the study are: (1) to determine whether or not a protective environment will permit adoption of an intensive chemotherapy regimen without increased risk to the patient, (2) to determine the therapeutic benefit of doses of chemotherapy much higher than those in general use, (3) to determine the value of a protective environment in the control of infection in immunosuppressed recipients of allogeneic marrow grafts, and (4) to evaluate the role of the nearly bacteria-free state in the development of graft-versus-host disease.